Scott Detrow

Updated at 10:20 a.m ET

Vermont Sen. Bernie Sanders pulled off a narrow victory in New Hampshire on Tuesday night, providing a jolt of energy to his front-of-the-pack status by holding off Pete Buttigieg, former mayor of South Bend, Ind.

Former Vice President Joe Biden is defending his record on Social Security, amid increased criticism from the campaign of Vermont Sen. Bernie Sanders, which has repeatedly pointed to Biden's willingness as a U.S. senator to back spending freezes for Social Security and other entitlement programs.

The candidates' back-and-forth culminated — as most disputes in modern presidential campaigns do — in dueling Twitter posts Tuesday night.

How confident are Iowa Democrats in their choices, now two weeks out from the caucuses?

The response Renee Kleinpeter gave NPR when asked which candidates she has narrowed her choice down to could sum it up: four seconds of laughter.

"I'll go with anybody who could beat [President] Trump," she said after laughing. "I wish somebody could tell me."

Updated at 5:11 p.m. ET

Leading Democratic presidential candidates on Tuesday blasted President Trump's decision to kill Iranian Maj. Gen. Qassem Soleimani, casting it as a dangerous escalation in a volatile region.

Former Vice President Joe Biden delivered a speech in New York City in which he labeled the deadly strike as the latest in a series of "dangerously incompetent" steps taken by Trump.

Just days after ending his campaign for president, former Housing and Urban Development Secretary Julián Castro is endorsing Massachusetts Sen. Elizabeth Warren.

The two will hold a rally together Tuesday evening in Brooklyn.

Updated at 2:06 p.m. ET

A three-month window that began with a heart attack ended as Vermont Sen. Bernie Sanders' strongest fundraising quarter yet.

Sanders' campaign announced it raised $34.5 million in October, November and December — nearly $10 million more than he had raised in the previous quarter. According to the campaign, $18 million came in from 900,000 individual donations in December alone, as Sanders drew larger and larger crowds to rallies in early voting states such as Iowa and New Hampshire.

Updated at 10:05 a.m. ET

The former law professor in the 2020 field is the only presidential candidate to earn an A in a new scorecard, released on Wednesday by the grassroots progressive group Indivisible.

Updated at 3:25 p.m. ET

California Sen. Kamala Harris is dropping out of the presidential race, citing a lack of funds. She informed her campaign staff of the decision on a conference call and later sent an email to supporters, in which she wrote "my campaign for president simply doesn't have the financial resources we need to continue."

Updated at 7:35 p.m. ET

Former New York Mayor Michael Bloomberg is weighing a late entrance into the Democratic presidential primary, reversing course from this spring, when he said publicly that he would not run.

Massachusetts Sen. Elizabeth Warren has been calling for President Trump's impeachment since the spring. California Sen. Kamala Harris wasn't too far behind her. New Jersey Sen. Cory Booker's been pushing for it for months.

In fact, all six U.S. senators still running for president are backing the House's impeachment inquiry.

But now that the lawmakers may be getting what they want, many political operatives see it as a train wreck for their presidential campaigns.

Former Vice President Joe Biden appears to be ramping up his attacks on President Trump. Notably, he's also ramping up his defense of his own dealings in Ukraine.

Updated at 3:43 p.m. ET

Former Vice President Joe Biden called for President Trump's impeachment unless the White House complies with congressional requests for information about a call the president made to a Ukrainian leader.

"We have a president who believes there is no limit to his power," Biden said. "We have a president who believes he can do anything and get away with it. We have a president who believes he is above the law."

Updated at 1:50 p.m. ET

Friends, family, reporters and politicians gathered Saturday in downtown Washington, D.C., to remember journalist Cokie Roberts.

She was hailed as a "servant" of God and referred to as a "special singular soul" by those who delivered remarks.

Roberts died Tuesday at age 75 of complications from breast cancer. She had covered and commented on politics for NPR since 1978 and spent decades working for ABC News as well, including several years co-hosting the Sunday morning political show This Week.

Updated at 1:40 p.m. ET

Security concerns have prompted the Democratic National Committee to recommend nixing a plan that would have allowed Iowans and Nevadans to remotely caucus for candidates next year.

Supporters have long argued that "virtual caucuses" would open up Iowa's first-in-the-nation presidential contest, which requires caucusers to physically attend sometimes hours-long events to declare their choice for president.

Former Vice President Joe Biden plays up his Pennsylvania roots as much as anything and has heavily courted organized labor in his presidential campaign, but a key union in Biden's backyard is feeling neglected by the leading Democratic candidate.

Sens. Elizabeth Warren and Bernie Sanders are campaigning on "big structural change" and "political revolution." Former Vice President Joe Biden thinks voters will weigh the "soul of America" as they decide whom to support.

Sen. Kamala Harris is making a different bet.

The California senator's campaign is increasingly focused on economic challenges that, as she framed it at the Iowa State Fair this weekend, wake voters up in the middle of the night.

Hoping to regain momentum as two rival candidates creep closer in the polls, Vermont Sen. Bernie Sanders returned to his signature policy theme in a major speech Wednesday: a single-payer, "Medicare for All" health insurance system.

"The time is now to go forward. The time is now to expand Medicare to every man, woman, and child in this country," Sanders told supporters and reporters in Washington, D.C.

Updated at 3:00 p.m. ET

President Trump has made undoing the Obama Administration's foreign policy record one of his top priorities. So it's no surprise that former Vice President Joe Biden — who played a key role in implementing now-abandoned agreements like the Paris climate agreement and the Iran nuclear deal, sees Trump's foreign policy as a disaster.

Former Vice President Joe Biden has referred to himself as "middle class Joe" throughout his political career, and used to regularly joke about being the "poorest person on Congress."

Those terms no longer apply.

Biden and his wife, Jill, have together earned more than $15 million since Biden left office. That's according to tax returns and other financial disclosure forms released by Biden's campaign on Tuesday. The bulk of the Bidens' earnings come from book sales and paid speaking engagements – two routine sources of income for former high-ranking public officials.

Massachusetts Sen. Elizabeth Warren spent most of the spring as the Democratic presidential hopeful on the rise.

Her poll numbers steadily ticked up, as she carved out a spot as a policy-focused candidate whose weekly plan rollouts set much of the broader campaign agenda.

The momentum translated to fundraising. Warren took in $19.1 million in April, May and June — more than three times what her campaign raised during the first quarter of 2019, according to her campaign Monday.

One of Vermont Sen. Bernie Sanders's most animated moments in Thursday night's Democratic debate came after California Rep. Eric Swalwell urged voters to "pass the torch" to a new generation of leaders.

Swalwell's critique was aimed at former Vice President Joe Biden. But despite the fact that Sanders has been increasingly critical of Biden's policy positions, the independent Senator tried to rush to his fellow septuagenarian's defense. "As part of Joe's generation, let me respond," he urged the moderators in the middle of a candidate free-for-all.

Updated at 1:15 p.m. ET Thursday

A former vice president, four senators, a representative, a former governor, a mayor and a pair of entrepreneurs walk onto a stage ... where 10 other candidates tried to get their messages across to voters on Wednesday night.

Millions of television viewers are getting their first extended look at the historically sprawling Democratic primary field over two nights in Miami this week.

Updated at 6:30 p.m. ET

The day after former Vice President Joe Biden recalled his "civil" and productive working relationships decades ago with two longtime segregationist and racist fellow lawmakers, fellow Democrats are pouncing.

At a New York City fundraiser Tuesday night, Biden told donors he has reached across the aisle throughout his career. "I was in a caucus with James O. Eastland," Biden said, according to a pool report. "He never called me 'boy'; he always called me 'son.' "

What will the first Democratic presidential debates look like at the end of this month?

We got our first glimpse Saturday in San Francisco.

First, we saw the visual of candidate after candidate — 11 in all, with 3 more to come Sunday — parading across the stage at the California Democratic Party's annual convention.

This weekend, 14 presidential candidates will converge on San Francisco for the California Democratic Party's annual convention.

It will be the largest gathering of presidential contenders so far, and the latest sign that California's days of bringing up the rear of the presidential primary calendar are long gone.